In recent years, miniaturization and high-performance in an electronic equipment such as portable telephones, etc. have been rapidly advanced, and keeping with this, an electric circuit in an electronic equipment has been made high packaging density and decreased in withstand voltage. Therefore, there has been increased damage to an electric circuit in an equipment, which is caused by electrostatic discharge pulse generated when the human body and terminals of the electronic equipment contact with each other.
Conventionally, as measures to prevent such damage caused by electrostatic discharge pulse, a method has been carried out to provide a multilayer chip varistor, etc. between the incoming line of electrostatic discharge pulse and the ground so as to bypass the electrostatic discharge to reduce voltage applied to an electric circuit of an electronic equipment.
For example, JP-A-8-31616 is known as prior art document information related to conventional multilayer chip varistors used in measures against electrostatic discharge pulse.
Recently, keeping with high-performance in an electronic equipment, clock frequency, at which an electronic equipment is operated, is increasingly made high. As a result, electronic parts such as the electrostatic discharge protection components have demanded a small electrostatic capacity that has no influence on clock frequency. Frequency for transmission and reception in portable telephones, etc. is as high as 800 MHz to 2 GHz, and electrostatic discharge protection components corresponding to this requires a small electrostatic capacity.
Since a zinc oxide material constituting conventional multilayer chip varistors has a dielectric constant in the order of several hundreds to one thousand and several hundreds, however, it is difficult to realize electrostatic capacity of at most 1 pF with stray capacitance. In case of, for example, a conventional multilayer chip varistor sized to conventionally have a length of 1.0 mm and a width of 0.5 mm, a minimum electrostatic capacity thereof is around 3 pF, a cutoff frequency thereof is in the order of about 1 GHz, and a resonant frequency thereof is about 1.8 GHz. Accordingly, use at a high frequency over 1 GHz is not possible.
The invention has been thought of in view of the problem and has its object to provide an electrostatic discharge protection component having a very small electrostatic capacity.